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Li-confinable core-shell hosts have been extensively studied because they mitigate Li dendrite growth and volume change by reducing the effective current density and storing Li inside the core space during consecutive cycling. However, despite these fascinating features, these hosts suffer from unwanted Li growth on their surface (i.e., top plating) due to the carbon shell hindering Li-ion movement especially at higher current densities and capacities, resulting in poor electrochemical performance. In this study, we propose a one-dimensional porous Li-confinable host with lithiophilic Au (Au@PHCF), which is synthesized by a scalable dual-nozzle electrospinning. Because of the well-interconnected conductive networks forming three-dimensional structure, porous shell design enabling facile Li-ion transport, and hollow core space with lithiophilic Au storing metallic Li, the Au@PHCF can suppress the Li top plating and improve the Li stripping/plating efficiency compared to their counterparts even at 5 mA cm

Microwave irradiation assists the transformation of acid-insoluble Klason lignin into a green adhesive at a low reaction temperature (100 °C) and short reaction time (10 min).

Direct visualization of the dissolution and deposition reactions in Se cathodes resolves the competitive nucleation and growth behaviors dependent on the depletion of electrolyte-soluble polyselenides.

Lithium (Li) metal emerges as an anode for high-energy-density Li metal batteries due to their high theoretical capacity (3860 mAh g−1) and low electrochemical potential (−3.04V versus standard hydrogen electrodes). Nonetheless, the inherent instability of Li metal against conventional carbonate-based electrolytes (denoted as carbonates), causing unpredictable reactions and unstable interphase layers, precludes the commercialization of Li metal batteries. Herein, an innovative strategy-hybrid polyion complex micelle to enable high-performance Li metal anodes in carbonates is reported. Ionized LiNO3 cooperates with block copolymer (polystyrene-block-poly(2-vinyl pyridine) (S2VP)) micelles via electrostatic interaction and plants on the Li metal surface together. The union with S2VP and ionized LiNO3 can shut off from contact with the Li surface and carbonates, construct the unique solid electrolyte interface layers with a Li-ion conductivity gradient, and control Li morphology. S2VP/LiNO3-Li metal electrodes enable high-efficiencies over 100 cycles and even at high-temperature with universal carbonates. S2VP/LiNO3-Li//LiNi0.8Co0.1Mn0.1O2 full cells achieve long-stable cycling over 300 cycles under harsh test conditions: limited-excess Li (thickness of 40 and 100 μm), high-areal capacity (4.0 mAh cm−2), and high-current density (4.0 mA cm−2). Moreover, a pouch-type full cell demonstrates commercial viability. This work provides new insights into enabling Li metal batteries with high-energy-density to adopt conventional carbonates. Data Availability: Data will be made available on request.

Dendrite-free lithium (Li) has been the primary issue for the practical application of metallic Li anode. Repeated Li plating/stripping is known to inevitably lead to severe volume changes and gradual Li dendrite growth, eventually resulting in irreversible Li (called dead-Li) as an unexpected feature. In order to avoid the dead-Li, a lithiophilic surface is highly desirable and a nanoarchitectured host for metallic Li is also required. Herein, cobalt-embedded, mesoporous, nitrogen-doped graphite (N-doped graphite) is strategically proposed as a new innovative Li-metal storage host. After tuning the surface chemistry, the material shows high Li ion affinity as well as a highly lithiophilic surface, which is attributed to the low formation energy of N-doped graphite, strongly supported by density functional theory calculations. As a result, the desirable anode shows excellent electrochemical performance with high Li-metal reversible capacity and even stable long-term cyclability with no dead-Li formation. Our findings pave the way to optimize the Li-metal host up to the limit of the theoretical capacity.

Li metal is considered the ultimate electrode for lithium-ion batteries due to its high specific capacity (3860 mAh g–1) and density (0.534 g cm–3). Despite these advantages, the practical use of L...

Designing a fast ionic conductor has been an essential issue in next-generation batteries based on all-solid-state systems, with specific application targets in large-scale energy storage devices. For this wide range of applications, high levels of ionic conductivity, as well as safety, should be preferentially ensured. However, current solid electrolyte technology is unable to meet the high standards of acceptable conductivity and becomes more problematic in multivalent-ion batteries. Herein, we have proposed a novel phase-convertible ionic conductor based on a monolithic succinonitrile (SN) plastic crystalline material. The unique properties of SN, with high polarity and high rotational degrees of freedom, enable it to dissolve Mg salts and allow for fast transport of cations in the solid phase. For the first time, a high Mg2+ ion conductivity of 2.8 × 10−5 S cm−1 was demonstrated at room temperature, and high chemical and thermal stabilities with a wide electrochemically stable window were proven. The monolithic SN structure was able to process simple phase transitions between liquids and solids; therefore, the highly deformable phase-convertible ionic conductor enabled the formation of excellent conformal contact with the electrode. In addition, the origin of the high conductivity was theoretically investigated through density functional theory calculations. We believe that the unique host of monolithic SN is a useful platform with potential applicability for most kinds of cation with fast ion-conducting properties.

Realizing Li-metal batteries requires overcoming several hurdles, such as volume changes, a thickening solid electrolyte interphase, and safety issues associated with uncontrollable Li growth. Introducing a 3D conductive framework that improves Li reversibility by decreasing the local current density and alleviating volume changes can mitigate these issues, but inevitable Li growth on the top surface remains problematic. To address this, herein, we report an electrical conductivity-controlled 3D host consisting of a glass fiber (GF) framework, size-/conductivity-controlled partially reduced graphene oxide (PrGO), and a Cu substrate (PrGO–GF/Cu). Due to the synergistic interplay between the 3D GF alleviating volume fluctuation and PrGO with desirable conductivity, the PrGO–GF/Cu host mitigates the Li top plating and guides preferential Li deposition/dissolution at the bottom of the structure. As a result, the PrGO–GF/Cu exhibits substantially improved electrochemical performance in coulombic efficiency, symmetric cell, and LiFePO4 full cell tests. Experimental and theoretical studies reveal that modulating the electrical conductivity of the framework within an optimal range is an easy and effective way of suppressing Li top plating and facilitating Li bottom plating/stripping. This work demonstrates the importance of controlling the electrical conductivity to enable reversible behavior of Li in the Li-metal host anode, and a facile method to fabricate a 3D host that prevents Li top plating.

Structure engineering in the crystal framework has tremendously emerged in perovskite solar cells (PSCs) to realize highly efficient devices with superior chemical and electrical properties. The introduction of organic spacer cation in the perovskite crystal is one of the major topics in the current state of structural engineering research. However, the intercalated organic molecules in the three-dimensional (3D) perovskite structure generate a low-dimensional perovskite phase, which results in inefficient carrier transport by the reduction of 3D dimensionality. To keep the 3D crystal structure in the organic cation-inserted perovskites remains the main issue, and a challenging task to be solved. In this work, we created an ideal organic-layered 3D crystal structure using an n-butylammonium (n-BA) halide salt in the FA0.83Cs0.17Pb0.5Sn0.5I3 perovskite. The cation allows the self-assembled hierarchical structure that n-BA organic analog is layered on the surface and in the bottom of the perovskite without the reduction of 3D crystal dimensionality. Through the X-ray scattering results, vertically oriented crystal structure in the external and internal structural perspective demonstrates the creation of the ideal n-BA capped 3D perovskite crystal. Furthermore, the naturally driven n-BA cation facilitates the enhancement of the device stability of Pb-Sn PSCs as the suppression of the generation of silver iodide in the top interface and degradation by sulfuric acid of PSS from poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) in the bottom interface. This structural effect and chemical stability lead to achieving a highly efficient Pb-Sn PSC with near 19 % efficiency.

The utilization of lithium (Li) metal is highly desirable, because it is the most attractive anode for high-energy Li batteries, even if there are problems with the unpredictable phenomena of dendritic growth and dead-Li during repeated plating-stripping. So far, the issue of branch-like uneven Li plating has still not been resolved. Recently, using a highly concentrated salt-electrolyte (lithium bis(fluorosulfonyl with a LiNO3 additive)) was recognized as the most straightforward approach, although its critical role still remains elusive. Herein, we investigated the overpotential of metallic Li anodes with electrolytes having different salt concentrations and verified the microscopic origins of Li growth, as observed by in situ optical microscopy. We argue that the high ionic conductivity of the electrolyte together with its solid-state interphase effectively suppresses the local potential and concentration gradients, resulting in highly dense dendrite-free Li plating, as supported by in-depth numerical analysis. Our findings provide clear insights that can pave the way to further improvements of the performance of Li metal anodes up to the theoretical limit (3860 mA h g−1).

In this study, newly designed cathode material LiFeP1-xSixO4, with silicon mixed in LiFePO4 is investigated using the density functional theory. Its most optimized structure is the olivine structure of the Pnma space group. Bonding length show the anti-site defect which hinders Li diffusivity is prevented in the LiFeP1-xSixO4. Lithium migration energy barriers in the (010) path of LiFeP1-xSixO4 (x = 0, 0.5, and 1) are calculated by using nudged elastic band calculations, and the average values are determined as 0.180, 0.245, and 0.280 eV for LiFePO4, LiFeP0.5Si0.5O4, and LiFeSiO4, respectively. This signifies that the Li ionic diffusivity is degraded thermodynamically, which is contrary to that indicates by the calculated bonding length, however, the difference is negligibly small. Furthermore, the intercalation voltage increases up to 4.97 V, depending on the Si ratio to P, and is much higher than that of the pristine cathode materials LiFePO4 (∼3.47 V) enabling voltage optimization by Si substitution. The energy density is proportional to the intercalation voltage, hence the energy density is increased, respectively. Finally, the Total density of states show that the electronic conductivity of LiFeP1-xSixO4 (x = 0–1) is better than that of LiFePO4.

The use of high-capacity electrode materials (i.e., Si) in Li-ion batteries is hindered by their mechanical degradation. Thus, oxides (i.e., SiO2) are commonly used to obtain high expected capaciti...

The realisation of fast-charging lithium-ion batteries with long cycle lifetimes is hindered by the uncontrollable plating of metallic Li on the graphite anode during high-rate charging. Here we report that surface engineering of graphite with a cooperative biphasic MoOx–MoPx promoter improves the charging rate and suppresses Li plating without compromising energy density. We design and synthesise MoOx–MoPx/graphite via controllable and scalable surface engineering, i.e., the deposition of a MoOx nanolayer on the graphite surface, followed by vapour-induced partial phase transformation of MoOx to MoPx. A variety of analytical studies combined with thermodynamic calculations demonstrate that MoOx effectively mitigates the formation of resistive films on the graphite surface, while MoPx hosts Li+ at relatively high potentials via a fast intercalation reaction and plays a dominant role in lowering the Li+ adsorption energy. The MoOx–MoPx/graphite anode exhibits a fast-charging capability (, Fast-charging of lithium-ion batteries is hindered by the uncontrollable plating of metallic Li on the graphite anode during cycling. Here, the authors demonstrate the fast chargeability and long cycle lifetimes via surface engineering of graphite with a cooperative biphasic MoOx–MoPx promoter.

Solid polymer electrolytes (SPEs) have been received significant attention due to their inherent advantages of high safety and high electrochemical stability as fast Li-ion conductors. However, conventional SPEs of dual-ion conductors (i.e., conducting both anions and cations) are prone to induce concentration polarization and thus decrease in ionic conductivities, which remains a significant hurdle for their practical applications. Here, we propose a new host of porous aromatic frameworks (PAFs) as a promising single Li-ion conducting SPEs. PAF1 is one of the promising types for crystalline polymers with the integration of aromatic organic building units into a 3-dimensional framework, having plenty of voids space inside. By covalently tethering the sulfonate on aromatic groups, anions are immobilized onto the frameworks, and the exchanging process of protons with Li-ions makes it perform as a fast Li-ionic conductor. Consequently, Li sulfonated PAF1 (denoted as Li-SPAF1) shows superior ion-conducting properties of 0.102 mS cm−1 at room temperature with the activation energy of 0.21 eV. It is demonstrated that the aromatic groups have high chemical and thermal stabilities, even stable with Li metal, which is advantageous for delivering stable electrochemical performances. Also, the structure and conduction mechanism are theoretically investigated by using density functional theory calculations.

Despite a variety of advantages over the presently dominant vanadium redox flow batteries, the commercialization of iron–chromium redox flow batteries (ICRFBs) is hindered by sluggish Cr2+/Cr3+ redox reactions and vulnerability to the hydrogen evolution reaction (HER). To address these issues, here, we report a promising electrocatalyst comprising Ketjenblack (KB) carbon with embedded bismuth nanoparticles (Bi-C). The uniform incorporation of Bi nanoparticles into KB carbon via a simple reduction process excellently promotes the electrochemical activity of Cr2+/Cr3+ redox reactions while retarding the HER. A combination of experimental analysis and density functional theory (DFT) calculations indicates that these phenomena are attributable to the synergistic effect of Bi and KB, which inhibits hydrogen evolution and provides active sites to enhance the Cr2+/Cr3+ redox reaction, respectively. An ICRFB cell containing the Bi-C catalyst as the negative electrode exhibits a high energy efficiency of 86.54% with excellent capacity retention during charge–discharge cycling at room temperature. This study offers an intelligent hybrid material as a useful design principle for electrocatalysts capable of addressing the critical problems in ICRFBs.

Ether-based organic liquid electrolytes (OLEs) have been commonly used in lithium–oxygen batteries (LOBs); however, they become unstable and cause rapid performance degradation during LOB operation. To address these problems, in this study we propose an OLE-free cathode architecture based on a Li+-selective solid membrane (LSSM). An LSSM with a seamless duplex (dense/porous) architecture is prepared by a tape casting process combined with co-sintering, and carbon nanotubes (CNTs) decorated with Au nanoparticles (CNT@Au) are directly formed on its porous framework. We show that the duplex-LSSM can effectively protect the metallic Li anode from parasitic reactions with impurity species and improve the cycling stability of Li. Furthermore, an LOB assembled with the duplex-LSSM and CNT@Au components exhibits a discharge capacity as high as 3650 mAh g−1 and improved cycling stability (>140 cycles) compared to a conventional OLE-based LOB; this can be explained in terms of the combined advantages provided by the OLE-free cathode and the LSSM-protected Li anode.

Lithium metal (Li) is an ideal anode for designing high-energy Li metal batteries (LMBs) due to its high specific capacity (3860 mAh g−1) and lowest electrochemical potential. However, the practical use of Li is currently impeded by uncontrollable dendritic growth during repeated Li plating and stripping, causing serious safety hazards such as electrical short circuits. To regulate Li growth behavior, various solid electrolyte interfaces (SEIs) have been explored. Despite intensive efforts, further understanding of the dendritic growth mechanism is still required. In this respect, herein, we clarify the origin and growth mechanism of Li dendrites by evaluating the critical role of an artificial SEI using a finite element method. Based on our theoretical study, we suggest that the relatively low ionic conductivity of the SEI layer is responsible for facilitating the growth of Li dendrites and the growth can be effectively suppressed by employing an artificial SEI with a higher ionic conductivity. The high-conductivity artificial SEI regulates local current distributions, directly affecting the growth of Li dendrites as determined by measuring the current density, exchange current density, and geometry. Our findings provide new insight into the design of artificial SEIs for improving the cycling performance of advanced LMBs.

In this study, we revealed the interfacial strengthening mechanism between a Stone- Thrower-Wales (STW) defective single layer graphene and polypropylene (PP), through a density functional theory (DFT) simulation and atomistic molecular dynamics simulations. In quantum mechanical simulation, the adhesion energy of propylene monomer on STW defective graphene is calculated with van der Waals interaction. An improved adsorption characteristic of propylene to the STW defective graphene is clearly observed, compared with a pristine counterpart. For deeper understanding of the adsorption, the electronic structure calculation and geometrical analysis of the adsorbed structures are also performed. In molecular dynamics simulation, three transversely isotropic nanocomposite unit cell structures consisting of PP and single layer graphene having a different number of STW defects are constructed. The stress-strain curves of nanocomposites according to the density of STW defects are obtained from uniaxial tension and shear tests. Since the properties of graphene itself are degraded by the STW defects, the overall stress-strain characteristics of nanocomposites involving the deformation of graphene are degraded by the addressed STW defects. However, in longitudinal shearing, where interfacial shearing between graphene and PP is involved, the STW defect can critically improve the shear load bearing capability. The increased interfacial shear load transfer is mostly attributed to the rippling of graphene at the STW defective sites, and the resultant surface roughness of graphene.

Silicon-based materials are the most promising candidates to surpass the capacity limitation of conventional graphite anode for lithium ion batteries. Unfortunately, Si-based materials suffer from poor cycling performance and dimensional instability induced by the large volume changes during cycling. To resolve such problems, nanostructured silicon-based materials with delicately controlled microstructure and interfaces have been intensively investigated. Nevertheless, they still face problems related to their high synthetic cost and their limited electrochemical properties and thermal stability. To overcome these drawbacks, we demonstrate the strategic design and synthesis of a gyroid three-dimensional network in a Si@SiOx/C nanoarchitecture (3D-Si@SiOx/C) with synergetic interaction between the computational prediction and the synthetic optimization. This 3D-Si@SiOx/C exhibits not only excellent electrochemical performance due to its structural stability and superior ion/electron transport but also enhanced thermal stability due to the presence of carbon, which was formed by a cost-effective one-pot synthetic route. We believe that our rationally designed 3D-Si@SiOx/C will lead to the development of anode materials for the next-generation lithium ion batteries.

The use of high-capacity electrode materials (i.e., Si) in Li-ion batteries is hindered by their mechanical degradation. Thus, oxides (i.e., SiO

Background Mucosal healing (MH) is one of the treatment targets in patients with ulcerative colitis (UC). However, it has been suggested that even in patients with MH, disease prognosis depends on histologic activity. This study aimed to evaluate histologic features predicting disease prognosis and their relationship with endoscopic findings in UC patients with MH. Methods We retrospectively reviewed the data of patients with UC who underwent colonoscopy or sigmoidoscopy with biopsy and evaluated eight histological features, including chronic inflammatory infiltrate, neutrophils in epithelium, ulceration, acute inflammatory cell infiltrate, basal plasmacytosis and serrated architectural abnormalities, as well as Nancy index (NI). Histologic variables predicting disease progression defined as starting corticosteroid, biologics, or small molecule agent, or undergoing clinical relapse or surgical operation were evaluated, and correlated with endoscopic findings. Results A total 194 biopsy specimens of 103 patients were evaluated. The highest grades of each histologic item were analyzed when biopsies were performed at multiple sites in one patient. 30.6% showed NI ≤ 1 (no acute inflammatory infiltrate) in 49 patients with endoscopic remission. Among 68 patients with MH, only 24.8% achieved NI ≤ 1. Mucosal friability in endoscopic findings was significantly associated with moderate-to-severe active histologic status (NI ≥3) (46.2% vs 80.0%, P=0.013), and patients with NI ≥3 showed significantly higher rates of disease progression during 13.7-month follow-up period (5.1% vs 19.0%, P=0.21). Ulceration and serrated architectural abnormalities were significantly associated with disease progression, and serrated architectural abnormalities was an independent risk factor in multivariate analysis (odds ratio 2.691 (95% confidence interval: 1.047–6.915), P=0.04). Conclusion Mucosal friability in endoscopic findings reflects moderate-to-severe active histologic status, and presence of serrated architectural abnormalities predicts disease progression in UC patients with MH. These findings may help identify patients need closer monitoring.

Despite their potential for achieving high energy density, anode-free batteries (AFBs) suffer from poor cycling stability caused by uncontrollable Li-metal deposition. To improve the reversibility of Li by physically preventing Li dendrite growth and minimizing the side reaction area between Li and the free solvent, two representative salts, lithium bis(fluorosulfonyl)imide (LiFSI) forming a robust/conductive LiF-based solid electrolyte interphase (SEI) layer, and LiNO3 altering the deposited Li morphology from dendritic to spherical, are widely used as salts for electrolyte. However, the depletion of LiNO3 by continuous consumption during cycling is a problem due to its low solubility. Thus, here, we report the use of high-concentration dual-salt electrolyte consisting of LiFSI and LiNO3 for AFBs to circumvent these issues. Experimental and theoretical studies reveal that electrolytes with high-concentration LiNO3 (up to 2 M) can be prepared by suppressing the agglomeration of LiNO3 in 1,2-dimethoxyethane (DME) in the presence of LiFSI. Because of the densely packed Li without dendrite, the formation of a protective SEI layer, and the alleviation of electrolyte oxidation as well as Al corrosion, the AFBs with this electrolyte achieve good cycling performance by reversible operation of Li. This work demonstrates the importance of electrolyte engineering for highly stable AFBs.

The mechanical properties of cathode materials are among the critical factors that directly affect the lifespan of lithium-ion batteries (LIBs). However, a significant challenge remains in understanding the exact mechanism of mechanical degradation of present cathode materials that results in significant loss of performance during long-term operation. Herein, a comparative study on the correlation between mechanical strength (e.g. particle hardness) and cycle performance of the cathode materials (particularly those with layered structures) is presented. By improving the particle hardness of cathode materials via Mg doping, the formation of undesirable microcracks within the particles during cycling can be effectively suppressed, thus improving cycle performance. Structural and electrochemical analyses are performed in order to further elucidate the mechanical degradation mechanism of LIBs during repeat cycles, and identify a possible approach to the enhancement of electrochemical performance and long-term durability in present cathode materials.

The kinetics of lithium atoms in various Li–Si binary compounds are investigated using density functional theory calculations and kinetic Monte Carlo calculations. The values of the Li migration energy barriers are identified by NEB calculations with vacancy–mediated, interstitial and exchange migration mechanisms in crystalline LiSi, Li12Si7, Li13Si4, and Li15Si4. A comparison of these NEB results shows that the vacancy–mediated Li migration is identified as the dominant diffusion mechanisms in Li–Si compounds. The diffusion coefficients of Li in Li–Si compounds at room temperature are determined by KMC simulation. From the KMC results, the recalculated migration energy barriers in LiSi, Li12Si7, Li13Si4, and Li15Si4 correspond to 0.306, 0.301, 0.367 and 0.320 eV, respectively. Compared to the Li migration energy barrier of 0.6 eV in crystalline Si, the drastic reduction in the Li migration energy barriers in the lithiated silicon indicates that the initial lithiation of the Si anode is the rate-limiting step. Furthermore, it is also found that Si migration is possible in Li–rich configurations. On the basis of these findings, the underlying mechanisms of kinetics on the atomic scale details are elucidated.

This work finds that LiVO3 is lithiated by a conversion reaction at 25 °C, which is unusual for the family of vanadium oxides. The spectroscopic studies and first-principle calculations performed on the lithiation mechanism of LiVO3 consistently propose that a two-phase insertion-type lithiation proceeds in the early stage of lithiation; LiVO3 transforms into a rock-salt structured Li2VO3. The continuing single-phase Li+ insertion into the tetrahedral sites in the rock-salt Li2VO3 produces a more Li-rich phase (Li2.5VO3), which is highly distorted because of the unfavorable Li+ insertion into the tetrahedral sites such as to be vulnerable to lattice breakdown. Hence, a two-phase (nucleation/growth type) conversion reaction is followed along with a structural disintegration; the Li2.5VO3 phase decomposes into metallic vanadium and Li2O. To determine the factors facilitating the conversion reaction of LiVO3, galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EI...

The electrochemical performance of Li-ion batteries strongly depends on the interaction between atomic scale and micro scale phenomena in high capacity electrode materials such as silicon and sulfur. Local thermodynamic interactions between host and guest species on atomic-scale significantly influence transfer kinetics and deformation kinematics on the micro-scale. We propose a multi-scale model to characterize the electrochemical and mechanical response of an amorphous silicon thin film during discharge/charge cycling. In the atomic-scale simulation, the stress-dependent energy barrier for the migration of lithium and the molar excess Gibbs free energy were calculated using density functional theory. These atomic-scale effects account for the nonlinear lithium diffusion behavior in the continuum simulation. In the continuum simulation, we considered the coupled diffusion and large deformation model on the cell-scale to determine the non-equilibrium cell potential as a function of the surface lithium concentration using Butler-Volmer kinetics. We clearly show that Li macroscopic kinetics is significantly affected by the stress induced by the volumetric strain associated with diffusion and the mixing formation energy of Li x Si. Our simulation results demonstrate that the multi-scale model is consistent with experimental observations at different C-rates.